Fix debian packaging ITP requirements

So i've submitted this package to Debian to be included into their archive. These changes are the results of that sponsorship. It adheres to the Debian policy and is lintian warning free :)

Also i've fixed a unittest error where shell output test were failing because $PATH was blank during the test. Not sure if that is intentional  or not but a hardcoded /usr/bin/python path doesn't seem that bad for unittests at this time.

Closes GH #122